Through electrostatics and examples of low-frequency alternating current and direct-current circuit, the problem of zero potential point is queried and clarified.

Selection of zero potential point in electrostatic field can be arbitrary in principle,however,it subjects to certain restrictions.

In the paper,universal calculation equation for gauging-point electric potential of oxidation-reduction titration reaction is discussed,testified and expressed exactly.

The discussion of electric potential reference point from some feign mistakes;